1. Field of the Invention
The present invention relates to a coating apparatus and a coated film manufacturing method.
2. Description of the Related Art
In the manufacturing of a coated film, for example, an optical film, a coating liquid is supplied to a continuously traveling web by a die coater. Generally, in a steady state, i.e., in a state in which the die coater and the web are brought into close contact with each other, coating is performed while forming a bead between a tip of the die coater and the web. An upstream side of the web is decompressed by a decompression chamber so as to continuously stabilize the bead.
In the coating using the die coater, so as to avoid trapping of air bubbles into a manifold of the die coater, a solvent is made to flow from the die coater in a non-steady state, i.e., in a state in which the die coater is detached from the web, that is, prior to the supply of the coating liquid from the die coater to the web. Then, switching from the solvent to the coating liquid is performed immediately before the steady state, i.e., the state in which the die coater and the web are brought into close contact with each other (JP2007-283260A).
During the coating by the die coater, when a joint portion at which the webs are jointed approaches the die coater, the die coater enters the non-steady state in which the die coater is retreated from the web, while ejecting the coating liquid. When the joint portion passes the die coater, the die coater returns the steady state in which the die coater approaches the web (JP2004-141806A).